Experimental Details

The gamma-ray detectors were from the TESSA3 array [3] and the beams were provided by the facility at Louvain-la-Neuve [4]. The beam was pulsed, with a repetition rate of 73ns. Evaporated charged particles were detected in the LEDA silicon array [5], protected from scattered beam using foils. In this experiment, known as `TaLL' (TESSA at Louvain-la-Neuve with LEDA), the gamma array was small (seven 25% detectors) and the unbacked target was relatively thick (1.6 mg/cm²). The forward hemisphere had no gamma detectors, and was open to allow the escape of scattered beam to the foils in front of LEDA, at a distance of 140mm. Only one pair of gamma detectors (two of the three at 90$^\circ$) faced each other through the target.

All events in which at least one escape suppressed gamma-ray was detected were written to tape. Any charged particles or other gamma-rays in slow coincidence (4$\mu$s) were also recorded. In addition, the gamma timing relative to the beam pulses was recorded, so that fast coincidences ($\pm 10$ns) could be analysed off-line.